Detection of g agents



DETECTION OF G AGENTS ethylamino) benzophenone oxime, which we designate 2,926,072 Patented Feb. 23, 1960 "ice EMK-O, respectively. Of these EMK-O appears to be the most sensitive and constitutes our presently preferred species.

David N. Kramer, Stevenson, Md., and Richard D. Morin, 5 The preferred activating agents are metallic ya Grandview Heights, and Robert H. Poitier, Columbus, o i y i e being preferred- Other cyanides that Ohio, assignors, by direct and mesne assignments, to have been used successfully are mercuric cyanide, potasflle United States Of America as represented y the siurn cyanide, silver cyanide and cadmium cyanide. The Secretary of the y oxime and cyanide may be mixed in the dry state in about No Drawing Application April 6, 1959 equal proportions and exposed to air suspected of con- Serial 804,550 taming vapors of the G agents.

Table I shows the characteristic color produced by dif- 3 Claimsferent combinations of oxime, cyanide and G agent in spot tests using the liquid G agent and on exposure to The invention described herein may be manufactured very dilute concentrations of vapors, 44 gamma (microand used by or for the Government of the United States grams) per liter of air.

Table I Oxlme Cyanide G Color Spot Test Color Dilute Vapors Agent red. 110x18. orange or red. pink in one second, orange .za aaa reddish orange.

MMK'O red orange igg orange. 4-Dimethylamlno-benzaldoxlme Slightly 4-Dlmethylamlno-acetophenone oxlme 4-Dimethylamino-benzophenone oxlme 4,4'-Tetramethyldlan1ino benzil monoxime kDimethylamino-4-nitro-benzophenone oxime of America for governmental purposes without the payment to us of any royalty thereon.

This invention is directed to the detection of' toxic chemical warfare agents of the class known as G agents. Important members of this class are GB or sarin (isopropyl methylphosphonofiuoridate), GA or tabun (ethyl dimethylphosphoroamidocyanidate), GD (pinacolyl methylphosphonofluoridate), and GF (cyclohexyl methylphosphonofluoridate.

Our method consists in contacting a fluid suspected of containing the agent with oximes of certain aromatic ketones containing at least one paradialkylamine substituent. These reagents show several important characteristics as detecting agents. When used alone, some of them show a color change with GA, but not with the other G agents listed above. With certain additives, however, they respond to the other agents as well. Thus, they may be used to distinguish between the phosphoroamidocyanidate, GA, and the phosphonofluoridates GB, GD and GF. Others give color reactions only in the presence of the additives, even with GA.

The compounds which we find most effective, and which give the reaction with GA in the absence of additives, are the oximes of Michlers ketone and its ethyl homologue, i.e., 4,4'-bis(dimethylamino) benzophenone oxime, which we designate MMK-O, and 4,4-bis (di- The oximes of 4-dimethylaminobenzaldehyde and 4- dimethylaminoacetophenone did not give a sufiiciently positive color change to be satisfactory for our purposes. The remaining compounds listed in the table are satisfactory, EMK-O and MMK-O being preferred, and EMK-O being presently regarded as the best.

The sensitivity of colorimetric detectors for chemical warfare agents is commonly expressed in terms of CT value, i.e., the product of the concentration (C) of the agent in the air expressed in gamma (micrograms) per liter of air multiplied by the time (T) in minutes to produce the change in color. The CT value for the blend of EMK-O with sodium cyanide was less than 1 gamma minute per liter, which is a very low value, indicating very high sensitivity.

The oxime detecting compositions may be utilized in the form of crayons. A typical crayon formulation is:

Component Percent Blane fixe (barium sulfate). NIK-O Sodium Cyanide the mark on a wall, for instance, is extremely sensitive, having a CT value for GB of less than 1 gamma minute per liter.

We claim:

1. A method for the detection of the presence in a fluid of a compound selected from the class consisting of ethyl dirnethylphosphoroamidocyanidate, isopropyl methylphosphonofiuoridate, pinacolyl methylphosphonofiuoridate and cyclohexyl rnethylphosphonofiuoridate, which comprises contacting said fluid with a compound selected from the class consisting of 4,4'-bis (dimethylamino) benzophenone oxime, 4,4'-bis (diethylamino) benzophenone oxime, 4-dimethylamino-4'-nitrobenzophenone oxime and 4,4-tetramethyl diaminobenzil monoxime in admixture with a compound selected from the class consisting of sodium cyanide, potassium cyanide, mercuric cyanide and silver cyanide.

2. A method for detecting the presence of ethyl dimethylphosphoroamidocyanidate in a fluid which comprises contacting said fiuid with a compound selected from the class consisting of 4,4-bis (dimethylamino) benzophenone oxime and 4,4-bis (diethylamino) benzophenone oxime.

3. A crayon for use in the detection of G agents comprising a compressed stick consisting essentially of a mixture of about 80 percent blanc fixe, 10 percent sodium cyanide and 10 percent 4,4-bis (diethylamino) benzophenone oxime.

References Cited in the file of this patent Young et al.: Anal. Chem. 30; 1236-39 (1958). Cherry et 21.: Anal. Chem. 30, 1239-47 (1958). 

1. A METHOD FOR THE DETECTION OF THE PRESENCE IN A FLUID OF A COMPOUND SELECTED FROM THE CLASS CONSISTING OF ETHYL DIMETHYLPHOSPHOROAMIDOCYANIDATE, ISOPROPYL METHYLPHOSPHONOFLUORIDATE, PINACOLYL METHYLPHOSPHONOFLUORIDATE AND CYCLOHEXYL METHYLPHOSPHONOFLUORIDATE, WHICH COMPRISES CONTACTING SAID FLUID WILTH A COMPOUND SELECTED FROM THE CLASS CONSISTING OF 4,4''-BIS (DIMETHYLAMINO) BENZOPHENONE OXIME, 4,4''-BIS (DIETHYLAMINO) BENZOPHENONE OXIME, 4-DIMETHYLAMINO-4''-NITROBENZOPHENONE OXIME AND 4,4''-TETRAMETTHYL DIAMINOBENZIL MONOXINE IN ADMIXTURE WITH A COMPOUND SELECTED FROM THE CLASS CONSISTING OF SODIUM CYANIDE, POTASSIUM CYANIDE, MERCURIC CYANIDE AND SILVER CYANIDE. 